Solid-state imaging apparatuses are required to have an improved S/N ratio and an increased dynamic range. In order to meet such requirements, an amplifying circuit and a detection circuit which detects the signal level of each pixel signal in each of columns of pixels arranged in a matrix are provided for each column in Japanese Patent Application Laid-Open No. 2004-015701. With this configuration, signal saturation in each column amplifying circuit is avoided, the gains of pixel signals are controlled such that small-amplitude ones are not saturated, and the gains are returned to the original values in a downstream circuit.
In Japanese Patent Application Laid-Open No. 2010-16416, a column amplifying circuit for each of columns generates a low-gain signal and a high-gain signal from each pixel signal from an imaging device. Signals obtained by returning high-gain signals to the same gain as the gain of low-gain signals and the low-gain signals are selectively combined to increase a dynamic range while maintaining an S/N ratio.
Japanese Patent Application Laid-Open No. H11-088166 describes a conversion error correction method at the time of AD conversion.
However, in the technique disclosed in Japanese Patent Application Laid-Open No. 2004-015701, a detection circuit for detecting a pixel signal is provided for each of columns of pixels, and a gain change is performed for each column. A circuit for controlling the configuration is more complicated, and a solid-state imaging apparatus occupies a larger area. In addition, the pixels have different S/N ratios.
In Japanese Patent Application Laid-Open No. 2004-015701 and Japanese Patent Application Laid-Open No. 2010-16416, a pixel signal is changed in gain by a column amplifying unit and is subjected to AD conversion. However, the disclosed techniques do not include detection of a gain error and an AD conversion error caused by the processing of the pixel signal and a method for correcting the errors. The technique disclosed in Japanese Patent Application Laid-Open No. H11-088166 is intended to correct a conversion error between before and after AD conversion in an AD converter itself. The technique is not a method for correcting a gain error between signals which are amplified at different gains by a plurality of column amplifying units and a plurality of column AD converters.